KELBURN, THANK YOU !
This is the EXACT thing I needed to see.... proves my point, EXACTLY. I am now of the firm beleif that we CAN (And DO) water gas shift in suction type gasifiers, where as, blown (pressureized) gasifiers can NOT do W/G shift. I think the W/G shift is at a great amount, BUT, it sure proves my caclulations, almost dead on. Thank you Thank you Thank you Thank you Greg On Sun, Mar 18, 2012 at 12:14 PM, Kelburn Koontz <[email protected]> wrote: > Making Ice with Vacuum > http://www.youtube.com/watch?v=pOYgdQp4euc > > Check out the ideal gas law. > > Thanks, > Kel > > > On Sun, 2012-03-18 at 08:10 -0700, Mark Ludlow wrote: >> “The steam produced in cavitation is like putting water in a bell jar >> and pulling a vacuum. If there is enough vacuum the water will boil, >> converting it's temperature into energy for the phase change. >> Eventually you end up with a chunk of ice in the bell jar.” >> >> >> >> Not so! Not enough latent heat is lost. Sensible heat must be removed >> also. In outer space, where there are huge radiative heat losses this >> applies. If folks could make ice with simple vacuum pumps, who would >> mess with refrigeration? It takes energy to evaporate water, not just >> vacuum. >> >> >> >> Plus, when a gas is adsorbed onto a sieve, energy is released. It >> takes the same energy (and then some) to regenerate the sieves. No >> free lunch; no where. >> >> >> >> >> >> From: [email protected] >> [mailto:[email protected]] On Behalf Of >> [email protected] >> Sent: Sunday, March 18, 2012 7:55 AM >> To: [email protected] >> Subject: Re: [Gasification] On the subject of H2 and O (was N2 >> removal) >> >> >> >> Hi Greg, >> >> >> >> >> >> Sure. Let's to a simple example so my feeble mind can follow it. >> When I drop cold chips in my gasifier there is some moisture content >> in the chips...this is liquid water in the wood cells. As the chips >> burn down into the hearth they get hot and the water changes to steam. >> This phase change absorbs some amount of energy. Then as the steam >> goes through the char, some of it does the water gas shift if there is >> enough heat. This absorbs even more energy. The remaining steam ends >> up as condensate in the cooler. >> >> >> >> >> >> The steam produced in cavitation is like putting water in a bell jar >> and pulling a vacuum. If there is enough vacuum the water will boil, >> converting it's temperature into energy for the phase change. >> Eventually you end up with a chunk of ice in the bell jar. >> >> >> >> >> >> The water gas shift will not happen in the phase change because there >> isn't sufficient activation energy availble to make the reaction go. >> If it did work that way, there would be hydrogen bubbles coming off >> boat propellers. That would make a COOL rooster tail! >> >> >> >> >> >> Gasifiers do not run a low enough pressure to vaporize the water, like >> the bell jar. I can get the numbers if you want, but you need to be >> in -13psi range. That's way more than we pull. >> >> >> >> >> >> Any clearer or still muddy?? >> >> >> >> >> >> Stephen >> >> >> -----Original Message----- >> From: Greg Manning <[email protected]> >> To: Discussion of biomass pyrolysis and gasification >> <[email protected]> >> Sent: Sun, Mar 18, 2012 10:09 am >> Subject: Re: [Gasification] On the subject of H2 and O (was N2 >> removal) >> >> Hi Stephen, thanks for the reply. >> >> OK, I somewhat understand you, BUT, wouldn't water be doing a phase >> change in the core of a gasifier as well ? >> >> What I was getting at, is if steam is produced in cavitation in cold >> water, then wouldn't the shift effect also happen within the core >> during phase transition (from water as a liquid, to water as a vapor, >> when heated by the core) within the same boundaries of effect as water >> to steam in the trailing edge of a propeller ? (all of these >> situations involve lower that normal pressure zones). >> >> Aren't contrails produced in water vapor on the wing tips of an >> airplane because of this same pressure drop phase shift, causing a >> dew-point change? >> >> The core of most gasifiers runs in a dynamic lower than atmospheric >> pressure ( a very low internal barometric pressure) (suction based >> units), so the same shifts should apply during phase transition, >> shouldn't they ? >> >> I understand that a pressure fed gasifier would behave differently >> (and I've personally observed this) than a suction based one, I'm >> speaking about suction based gasifiers. >> >> Somewhat lost, >> Greg >> >> >> On Sun, Mar 18, 2012 at 8:26 AM, <[email protected]> wrote: >> > Greg, >> > >> > The energy doesn't change. The bond energy in the water is constant >> > regardless of pressure. >> > >> > The cavitation issue is different. It is a phase change phenomenon, not a >> > chemical change one. >> > >> > Stephen >> > -----Original Message----- >> > From: Greg Manning <[email protected]> >> > To: Discussion of biomass pyrolysis and gasification >> > <[email protected]> >> > Sent: Sun, Mar 18, 2012 9:02 am >> > Subject: [Gasification] On the subject of H2 and O (was N2 removal) >> > >> > Greetings List. >> > Since we are speaking input air, I thought I might ask a somewhat >> > related question. >> > Water gas shift. I know there are many that have talked about this, >> > and I understand the basics. >> > However, here is the question. >> > At what negative pressure ( negative in/wc) does the shift move down >> > the temperature scale, to the point of being within the 1000 - 1200 c >> > area ? >> > We all know that propeller cavitation produces steam in water that is >> > 10 c (or there abouts), I have to assume (not being a chemist) that >> > the same negative pressure effect would also apply to other principals >> > when dealing with water. >> > -- >> > Regards, >> > Greg Manning, >> > Brandon, Manitoba, Canada >> > _______________________________________________ >> > Gasification mailing list >> > to Send a Message to the list, use the email address >> > [email protected] >> > to UNSUBSCRIBE or Change your List Settings use the web page >> > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org >> > for more Gasifiers, News and Information see our web site: >> > http://gasifiers.bioenergylists.org/ >> > >> > >> > _______________________________________________ >> > Gasification mailing list >> > >> > to Send a Message to the list, use the email address >> > [email protected] >> > >> > to UNSUBSCRIBE or Change your List Settings use the web page >> > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org >> > >> > for more Gasifiers, News and Information see our web site: >> > http://gasifiers.bioenergylists.org/ >> > >> >> >> >> -- >> Regards, >> >> Greg Manning, >> Brandon, Manitoba, Canada >> >> _______________________________________________ >> Gasification mailing list >> >> to Send a Message to the list, use the email address >> [email protected] >> >> to UNSUBSCRIBE or Change your List Settings use the web page >> http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org >> >> for more Gasifiers, News and Information see our web site: >> http://gasifiers.bioenergylists.org/ >> _______________________________________________ >> Gasification mailing list >> >> to Send a Message to the list, use the email address >> [email protected] >> >> to UNSUBSCRIBE or Change your List Settings use the web page >> http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org >> >> for more Gasifiers, News and Information see our web site: >> http://gasifiers.bioenergylists.org/ > > > > _______________________________________________ > Gasification mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org > > for more Gasifiers, News and Information see our web site: > http://gasifiers.bioenergylists.org/ -- Regards, Greg Manning, Brandon, Manitoba, Canada _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
